Conventionally, as disclosed in Patent Reference 1, there is proposed a robot skin equipped with tactile sensors discretely allocated at intervals on a base, an internal skin (first member) made of a high-stiffness material that is located on the tactile sensors to fully cover them and an external skin (second member) made of a low stiffness material having high coefficient of friction that is located on the internal skin to cover it, which is configured to use the tactile sensors to detect a load generated by a contact with an external object through the internal skin.
Patent Reference 2 discloses a robot skin that is equipped with matrix-arranged tactile sensors installed on an outer surface (base) and a pseudo skin (first member) made of silicon and located on the tactile sensors, and is configured to detect a load generated by a contact with an external object based on changing amount of capacitance. In the technique taught in Patent Reference 2, the pseudo skin is bored by holes of convex shape in section at a layer above a sensing point where comb electrodes of the tactile sensors intersect, projections having the same shape are each inserted therein, and ends of the projections are projected from the pseudo skin surface to be able to contact with an external object, such that a load from the external object acts on the sensing point through the projections.    Patent Reference 1: Japanese Patent Publication Hei 7 (1995)-8477    Patent Reference 2: Japanese Laid-Open Patent Application No. 2004-230532